Refrigeration to avoid contamination by a hydrocarbon

ABSTRACT

To avoid spillage of a potential contaminant normally fluid at ambient temperatures, a tanker used for transportation of such fluid will be so built and so operated that the cargo will be chilled to a temperature below the point at which it will congeal. Petroleum is an example of such a fluid. Before delivery, the petroleum or other cargo is to be raised to a temperature at which it is again fluid and can be pumped from the storage tanks in which it has been transported. From a method standpoint, a series of tankers can be served by a single high capacity refrigeration device at the port of embarkation, each tanker requiring, therefore, only minimum refrigeration equipment to maintain the paraffin-congealing temperature during transit. Similarly a single high capacity heating system will serve a succession of tankers to restore the contents to fluidity as a port of debarkation. By way of example, the cargo is assumed to comprise petroleum such as crude oil. Most hydrocarbon oils contain substantial quantities of paraffin and may, therefore, be congealed. In the case of crude oil, the temperature below which the oil cannot be poured will ordinarily range no lower than -70*F. Most are well above that temperature. A text book gives the pour point of Pennsylvania crude oil at 4.*F. The pour points given for Oklahoma, Colorado and certain Texas-Louisiana oils are 5.*F. Many other crudes will congeal at -15 or -20. Some even congeal at temperatures of 90*F. or higher. In one embodiment, it is contemplated that much of the entire interior of the hull may be devoted to the petroleum product. Since the temperatures at which the petroleum cargo congeals are far below the freezing point of water, even saline water, the hull is preferably well insulated and it may be encircled by a pipe which discharges air bubbles upwardly along the hull to displace sea water which might otherwise freeze thereon, particularly when the ship is at rest. This pipe also keeps free floating ice in ice laden waters away from the hull and keeps the ship from being frozen tight while at rest in this same type of water. These air bubbles also lessen the friction between the ice and the hull when the ship is in motion.

United States Patent [1 1 Abendroth [451 Nov. 20, 1973 REFRIGERATION TOAVOID CONTAMINATION BY A HYDROCARBON [76] Inventor: John Carl Abendroth,4238 W.

Hawthorne Trace Rd., Milwaukee, Wis. 53209 [22] Filed: Oct. 26, 1971[211 Appl. No.: 192,655

Primary Examiner-Manuel A. Antonakas AttorneyS. L. Wheeler et al.

[5 7] ABSTRACT To avoid spillage of a potential contaminant normallyfluid at ambient temperatures, a tanker used for transportation of suchfluid will be so built and so operated that the cargo will be chilled toa temperature below the point at which it will congeal. Petroleum is anexample of such a fluid. Before delivery, the petroleum or other cargois to be raised to a temperature at which it is again fluid and can bepumped from the storage tanks in which it has been transported. From amethod standpoint, a series of tankers can be served by a single highcapacity refrigeration device at the port of embarkation, each tankerrequiring, therefore, only minimum refrigeration equipment to maintainthe paraffin-congealing temperature during transit. Similarly a singlehigh capacity heating system will serve a succession of tankers torestore the contents to fluidity as a port of debarkation.

By way of example, the cargo is assumed to comprise petroleum such ascrude oil. Most hydrocarbon oils contain substantial quantities ofparaffin and may, therefore, be congealed. 1n the case of crude oil, thetemperature below which the oil cannot be poured will ordinarily rangeno lower than 70F. Most are well above that temperature. A text bookgives the pour point of Pennsylvania crude oil at 4.F. The pour pointsgiven for Oklahoma, Colorado and certain Texas-Louisiana oils are 5.F.Many other crudes will congeal at 15 or 20. Some even congeal attemperatures of 90F. or higher.

11 Claims, 3 Drawing Figures l9 9 9 G) '3 B REFRIGERATION TO AVOIDCONTAMINATION BY A IIYDROCARBON CROSS REFERENCE TO PREVIOUS APPLICATIONThis application is a companion to my co-pending application Ser. No.113,328, filed Feb. 8, 1971, for an Ice-Channel Cutting Attachment forShips.

BACKGROUND OF INVENTION peratures which usually are not as low as, andno lower than, 70F.

SUMMARY OF INVENTION In terms of apparatus and method, the inventioncontemplates .transportation of crude oil and other like products incongealed form so that the liquid cargo will not escape from thetransporting tanker even if the hull of the tanker is damaged. Therefrigerating mechanism may, in some embodiments, comprise cooling coilsat or near an insulated tanker wall, and which coils constitute theevaporator of a refrigeration system. The refrigerant lines or coils maybe so placed as'to allow for the necessary cooling throughout the cargoso that at the time of embarking the entire cargo is congealed. As theoil or the like is loaded it immediately begins undergoing the coolingprocess. Any section or compartment of the ship can be controlledseparately. This separate manual or automatic tank control enables theoil or product in the immediate vicinity or in adjacent tanks near apuncture or break in the ships hull to be still refrigerated in spite ofthe failure. The continued cooling in such an event will prevent the oilfrom entering the water. Normally with a hull failure or puncture theoil contained in the damaged tank immediately flows out of the confinesof the ship and is soon spread over a large surface of water, and anyaction to restrain the oil is accomplished after the spill. In thisinvention the spill is prevented from occurring or, at least in a verymajor break, due to the state of the oil there is time to act torestrain whatever oil might begin to move from its tank.

If the crude oil cargo had been congealed before the carrier leavesport, it will not escape even if the hull is accidentally punctured orbroken. The cargo will tend to remain gelatinous or like a chunk ofparaffin. Lake or sea water freezing on the oil because of its lowtemperature would act as insulation and as a secondary hull. Since therefrigeration requirements during transport are greatly reduced afterthe desired low temperature has once been attained, it is only necessaryto provide modest refrigerating capacity on the individual ships.

The method can be practiced without substantial refrigeration if, inlieu thereof, or as a supplement thereto, a congealing component such asparaffin, which is normally congealed at ambient temperature, isintroduced into the oil or fuel which constitutes the prime cargo.

By the same token, the heating mechanism required to restore thepetroleum to fluidity can serve a whole succession of ships at a port ofdebarkation.

Additional features of the invention include: (a) introducing bubbles ofgas along the side walls of the tanker (b) minimizing wave motion withinthe tanker by congealing the cargo and (c) using either or both areduced temperature or a congealing additive to congeal the cargo and tokeep the cargo congealed.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagrammatic cross sectionthrough a hull madein accordance with this invention for transportationof petroleum and the like in congealed form.

FIG. 2 is a view in end elevation showing a ship hull moored to a wharfhaving large capacity refrigeration and/or heating mechanism to serve asuccession of such hulls.

FIG. 3 is a fragmentary diagrammatic external view showing a portion ofa hull equipped with an encircling pipe for discharging air bubbleswhich, floating up the side of the hull, will prevent the freezing ofice on the hull surface.

DETAILED DESCRIPTION The hull 10 per se may be of any appropriateconstruction. Preferably it will be divided by partitions 11. Thepresent invention contemplates that it will have interior insulation at12 which may be foam or sheet or other insulation adherent adhesively orotherwise to the interior of the hull. Normally, in immediate proximityto the insulation 12, there will be a refrigeration coil 14 which maycomprise one or more convolutions in endless series. I use thetermendless series to indicate that the refrigeration coil 14 is in seriesconnection through pipe 16 with a condenser diagrammatically illustratedat 18 and to which refrigerant is supplied by compressor 20, thecompressor having an intake pipe 22 in series connection with the otherexpansion end line 14 and connected by pipe 24 to deliver the compressedrefrigerant to the condenser 18, whereby one well-known type ofrefrigerating system is in series with the expansion coil 14 whichabsorbs heat to be rejected from the condenser.

It is conventional in many refrigeration systems not to use therefrigerant directly for the ultimate cooling task. Accordingly, themethod herein disclosed contemplates the possiblity that therefrigerating system may chill a circulatory current of lowfreezing'point liquid which will then pass through the refrigerationcoils to cool the cargo.

While FIG. 1 shows the refrigerating mechanism directly mounted on deck32 of the hull l0, and while refrigerating mechanism of modest capacityisrequired to maintain the congealed state of the cargo duringtransportation, it is preferred that the initial chilling of the cargoto congeal the crude oil or other material should be done by a largecapacity refrigeration system such as that diagrammatically illustratedat 34 in FIG. 2. It is connected to the space or coils provided in thehull for the refrigerant. On the same wharf or on a like wharf at adelivery point, a large scale heating plant may be provided as shown at38, the arrangement being such that this will deliver a gas or highlyheated liquid through the pipe 40 into the coils 14, or parallel coils,or other space for heating fluid in .the interior of the hull.

Since the hull diagrammatically shown in FIG. 1 at 10 may be operatingin channels 56 through ice floes 58, and since the hull itself willunavoidably tend to absorb heat by virtue of the refrigeration of thecoils 14 or convection spaces 52 which are present, it is desirable toprovide means for preventing the hull from becoming frozen in ice,particularly during a period in which it may be at rest. To this end,pipe 60 encircling the hull well below the level at which the water 62is frozen is supplied with air through any appropriate compressor. Thepipe has a series of discharge openings 64 which are preferably directeddownwardly and inwardly toward the hull to release air bubbles such asthose shown at 66. These bubbles rising beside the hull tend to carryupwardly along the hull surface water which is warmer than that of thesurface and which, both by reason of its temperature and its motion willtend to keep ice from freezing on the surface of the hull. Theperforated compressed air line around a refrigerated tanker ship may besupplied with air heated due to the process of compression of therefrigerant in condenser 18 or otherwise. It being understood that thewhole mechanical disclosure is diagrammatic, I have shown on adiagrammatic basis, a motor-driven compressor 68 having an output pipe70 communicating with the pipe 60 for delivering air to the latter.

In terms of method, it is quite immaterial precisely how the cargo ofcrude oil or the like is refrigerated. Above suggested are arrangementsfor:

l. Passing compressible refrigerant from a condenser to one or more setsof convolutions of one or more evaporator coils to which the cargo isexposed in heat conductive relation.

2. Using conventional refrigeration machinery to chill a non-freezingliquid which can be circulated through such coils to absorb heat fromthe cargo.

3. Since, as the temperature decreases, the viscosity of the crude oilincreases due to the paraffins separating out as waxy solids, anotheraspect of the invention would be to add paraffin or other high meltingpoint solids to the crude oil at the port of embarkation and therebybring about the congealing of the crude oil with a less reduction intemperature. This extra paraffin can either be brought by the receivingship itself or be stored at the port prior to being heated and added tothe oil. Later this high melting point solid can be removed at arefinery or other appropriate location and can be reused, if desired,for the same purpose.

In all of these arrangements, the essential feature consists in handlingtransportation in whole or principal part while the cargo is congealed.

It is also true, of course, that a liquid of any type used as ananti-freeze liquid in an automobile radiator, or such a well-knownrefrigerant as ammonia, may be employed to reduce the temperature of thecrude oil or like cargo to the points where its paraffin content causesit to congeal. The circulatory fluid used to reheat the oil above itspour point will desirably comprise either ammonia or ethylene glycol. Itis desirable for the same fluid to be used for both processes so as toeliminate the necessity of two pipe systems or the draining of the linesfor the changeover.

The congealed state of the cargo eliminates the problems of stabilitywith tanker ships due to the free surface otherwise found with liquidcargo, for, for, as the ship is heeled, the liquid surface tends toremain horizontal. Also related to ship stability (and again eliminated)is free communication with the sea such as occurs when a liquid cargoflows from a fractured or punctured tank thereby allowing sea or lakewater to flow freely in or out of the damaged compartment.

Great advantages are perceived in using heavy duty refrigerationequipment which functions successively on several carriers of this type,thus making it unnecessary for the individual carrier to be equippedwith refrigerating mechanism other than just sufficient to maintain thecargo congealed during transport.

I claim:

1. A method of avoiding ecological contamination by accidental releaseduring transporting of a potential petroleum contaminant which isnormally liquid at ambient temperatures, such method consisting inproviding a vessel with a storage container with a refrigeration coil inthe container for heat exchange contact with the petroleum and providinga source of refrigerant on the vessel for circulation through said coil,filling the container with the liquid to be transported, reducing thetemperature of such liquid below the point at'which it congeals bycirculating a refrigerant through said coil, transporting the containerand liquid while congealed, and raising the temperature of the congealedcontainer contents to restore the potential contaminant to a liquidstate for removal from the container at the point of debarkation.

2. A method according to claim 1 which includes providing a docksidesource of refrigerant, making a massive reduction in the temperature ofthe potential contaminant fluid before embarking by connection of saidcoil to a dockside source of refrigerant and thereafter keeping it onlysufficiently cool to maintain the congealing thereof by use of therefrigerant source on the vessel.

3. A method according to claim 1 including the step of causing thecongealing of the fluid by adding a congealing component thereto.

4. A method according to claim 1 in which the point of debarkation isprovided with a source of heated fluid and the petroleum is raised intemperature by connection of the coil to the source of heated fluid andcirculating heated fluid through the coil to restore it to liquidity.

5. A method according to claim 2 in which the potential contaminant is ahydrocarbon oil containing paraffin.

6. A method according to claim 1 in which the said petroleum containsparaffin and in which the petroleum is lowered in temperature to a valuematerially below the pour point of said petroleum.

7. A method according to claim 1 in which the liquid to be transportedis introduced into a carrier and the step of reducing its temperature isperformed successively on a series of such carriers, the step ofmaintaining the temperature of the liquid below the pour point duringtransportation being performed separately on respective carriers.

8. A method according to claim 7 in which the step of modifying thetemperature is performed by means not transported by the carrier.

9. Amethod according to claim 7 in which the temperature of the fluid tobe transported is modified on a large scale in port and is only changedon a small scale while in transit.

10. A method according to claim 1 in which the carrier is a vessel and acompressed fluid is released into the carrier-supporting waterexternally about the vessel to prevent the vessel hull from becomingfrozen in ice.

6 1 1. A method of avoiding ecological contamination ing paraffin andreducing the temperature of such fluid by accidental release duringtransporting of a hydrocarbelow the point at which it congeals andtransporting bon which is normally fluid at ambient temperatures, thefluid while congealed.

said method consisting of congealing the fluid by add-

1. A method of avoiding ecological contamination by accidental releaseduring transporting of a potential petroleum contaminant which isnormally liquid at ambient temperatures, such method consisting inproviding a vessel with a storage container with a refrigeration coil inthe container for heat exchange contact with the petroleum and providinga source of refrigerant on the vessel for circulation through said coil,filling the container with the liquid to be transported, reducing thetemperature of such liquid below the point at which it congeals bycirculating a refrigerant through said coil, transporting the containerand liquid while congealed, and raising the temperature of the congealedcontainer contents to restore the potential contaminant to a liquidstate for removal from the container at the point of debarkation.
 2. Amethod according to claim 1 which includes providing a dockside sourceof refrigerant, making a massive reduction in the temperature of thepotential contaminant fluid before embarking by connection of said coilto a dockside source of refrigerant and thereafter keeping it onlysufficiently cool to maintain the congealing thereof by use of therefrigerant source on the vessel.
 3. A method according to claim 1including the step of causing the congealing of the fluid by adding acongealing component thereto.
 4. A method according to claim 1 in whichthe point of debarkation is provided with a source of heated fluid andthe petroleum is raised in temperature by connection of the coil to thesource of heated fluid and circulating heated fluid through the coil torestore it to liquidity.
 5. A method according to claim 2 in which thepotential contaminant is a hydrocarbon oil containing paraffin.
 6. Amethod according to claim 1 in which the said petroleum containsparaffin and in which the petroleum is lowered in temperature to a valuematerially below the pour point of said petroleum.
 7. A method accordingto claim 1 in which the liquid to be transported is introduced into acarrier and the step of reducing its temperature is performedsuccessively on a series of such carriers, the step of maintaining thetemperature of the liquid below the pour point during transportationbeing performed separately on respective carriers.
 8. A method accordingto claim 7 in which the step of modifying the temperature is performedby means not transported by the carrier.
 9. A method according to claim7 in which the temperature of the fluid to be transported is modified ona large scale in port and is only changed on a small scale while intransit.
 10. A method according to claim 1 in which the carrier is avessel and a compressed fluid is released into the carrier-supportingwater extErnally about the vessel to prevent the vessel hull frombecoming frozen in ice.
 11. A method of avoiding ecologicalcontamination by accidental release during transporting of a hydrocarbonwhich is normally fluid at ambient temperatures, said method consistingof congealing the fluid by adding paraffin and reducing the temperatureof such fluid below the point at which it congeals and transporting thefluid while congealed.